
/****************************************************************************
**
** Copyright (C) 2004-2008 VATATA.com . All rights reserved.
**
** This file is the part of the Miniutil Poject.
** Vatata's miniutil library is lightweight and portable (for linux
** and Windows). The C++ Class Library included Threadpool, Dll danymic loading, 
** General socket application model and tcp server, httpserver/servlet, etc. 
** It is a pratical utility disigned for who don't want learn the Big C++ 
** Developing Platform, such as  Boost or ACE.
**
** This file may be used under the terms of the GNU General Public
** License versions 2.0 or 3.0 as published by the Free Software
** Foundation and appearing in the files LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file.  Alternatively you may (at
** your option) use any later version of the GNU General Public
** License if such license has been publicly approved by VATATA.com.
** (or its successors, if any) and the Miniutil Project Aministrators. 
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://www.gnu.org/licenses/lgpl.html. If you are unsure which 
** license is appropriate for your use, please review the following 
** information: http://code.google.com/p/miniutil/ or contact 
** http://www.vatata.com.
**
** In addition, as a special exception, VATATA.com, as the sole
** copyright holder for Miniutil Project, grants users of VATATA
** P2P Platform the right to release and package with the related 
** libraries without the source code.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. vatata reserves all rights not expressly
** granted herein.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/


/*	$OpenBSD: queue.h,v 1.31 2005/11/25 08:06:25 otto Exp $	*/
/*	$NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $	*/

/*
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)queue.h	8.5 (Berkeley) 8/20/94
 */

#ifndef	_SYS_QUEUE_H_
#define	_SYS_QUEUE_H_

/*
 * This file defines five types of data structures: singly-linked lists, 
 * lists, simple queues, tail queues, and circular queues.
 *
 *
 * A singly-linked list is headed by a single forward pointer. The elements
 * are singly linked for minimum space and pointer manipulation overhead at
 * the expense of O(n) removal for arbitrary elements. New elements can be
 * added to the list after an existing element or at the head of the list.
 * Elements being removed from the head of the list should use the explicit
 * macro for this purpose for optimum efficiency. A singly-linked list may
 * only be traversed in the forward direction.  Singly-linked lists are ideal
 * for applications with large datasets and few or no removals or for
 * implementing a LIFO queue.
 *
 * A list is headed by a single forward pointer (or an array of forward
 * pointers for a hash table header). The elements are doubly linked
 * so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before
 * or after an existing element or at the head of the list. A list
 * may only be traversed in the forward direction.
 *
 * A simple queue is headed by a pair of pointers, one the head of the
 * list and the other to the tail of the list. The elements are singly
 * linked to save space, so elements can only be removed from the
 * head of the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the
 * list. A simple queue may only be traversed in the forward direction.
 *
 * A tail queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or
 * after an existing element, at the head of the list, or at the end of
 * the list. A tail queue may be traversed in either direction.
 *
 * A circle queue is headed by a pair of pointers, one to the head of the
 * list and the other to the tail of the list. The elements are doubly
 * linked so that an arbitrary element can be removed without a need to
 * traverse the list. New elements can be added to the list before or after
 * an existing element, at the head of the list, or at the end of the list.
 * A circle queue may be traversed in either direction, but has a more
 * complex end of list detection.
 *
 * For details on the use of these macros, see the queue(3) manual page.
 */
 
 namespace miniutil
{
    namespace upnp
    {


        #ifdef QUEUE_MACRO_DEBUG
        #define _Q_INVALIDATE(a) (a) = ((void *)-1)
        #else
        #define _Q_INVALIDATE(a)
        #endif

        /*
         * Singly-linked List definitions.
         */
        #define SLIST_HEAD(name, type)						\
        struct name {								\
            struct type *slh_first;	/* first element */			\
        }
         
        #define	SLIST_HEAD_INITIALIZER(head)					\
            { NULL }

        #ifdef SLIST_ENTRY
        #undef SLIST_ENTRY
        #endif

        #define SLIST_ENTRY(type)						\
        struct {								\
            struct type *sle_next;	/* next element */			\
        }
         
        /*
         * Singly-linked List access methods.
         */
        #define	SLIST_FIRST(head)	((head)->slh_first)
        #define	SLIST_END(head)		NULL
        #define	SLIST_EMPTY(head)	(SLIST_FIRST(head) == SLIST_END(head))
        #define	SLIST_NEXT(elm, field)	((elm)->field.sle_next)

        #define	SLIST_FOREACH(var, head, field)					\
            for((var) = SLIST_FIRST(head);					\
                (var) != SLIST_END(head);					\
                (var) = SLIST_NEXT(var, field))

        #define	SLIST_FOREACH_PREVPTR(var, varp, head, field)			\
            for ((varp) = &SLIST_FIRST((head));				\
                ((var) = *(varp)) != SLIST_END(head);			\
                (varp) = &SLIST_NEXT((var), field))

        /*
         * Singly-linked List functions.
         */
        #define	SLIST_INIT(head) {						\
            SLIST_FIRST(head) = SLIST_END(head);				\
        }

        #define	SLIST_INSERT_AFTER(slistelm, elm, field) do {			\
            (elm)->field.sle_next = (slistelm)->field.sle_next;		\
            (slistelm)->field.sle_next = (elm);				\
        } while (0)

        #define	SLIST_INSERT_HEAD(head, elm, field) do {			\
            (elm)->field.sle_next = (head)->slh_first;			\
            (head)->slh_first = (elm);					\
        } while (0)

        #define	SLIST_REMOVE_NEXT(head, elm, field) do {			\
            (elm)->field.sle_next = (elm)->field.sle_next->field.sle_next;	\
        } while (0)

        #define	SLIST_REMOVE_HEAD(head, field) do {				\
            (head)->slh_first = (head)->slh_first->field.sle_next;		\
        } while (0)

        #define SLIST_REMOVE(head, elm, type, field) do {			\
            if ((head)->slh_first == (elm)) {				\
                SLIST_REMOVE_HEAD((head), field);			\
            } else {							\
                struct type *curelm = (head)->slh_first;		\
                                            \
                while (curelm->field.sle_next != (elm))			\
                    curelm = curelm->field.sle_next;		\
                curelm->field.sle_next =				\
                    curelm->field.sle_next->field.sle_next;		\
                _Q_INVALIDATE((elm)->field.sle_next);			\
            }								\
        } while (0)

        /*
         * List definitions.
         */
        #define LIST_HEAD(name, type)						\
        struct name {								\
            struct type *lh_first;	/* first element */			\
        }

        #define LIST_HEAD_INITIALIZER(head)					\
            { NULL }

        #define LIST_ENTRY(type)						\
        struct {								\
            struct type *le_next;	/* next element */			\
            struct type **le_prev;	/* address of previous next element */	\
        }

        /*
         * List access methods
         */
        #define	LIST_FIRST(head)		((head)->lh_first)
        #define	LIST_END(head)			NULL
        #define	LIST_EMPTY(head)		(LIST_FIRST(head) == LIST_END(head))
        #define	LIST_NEXT(elm, field)		((elm)->field.le_next)

        #define LIST_FOREACH(var, head, field)					\
            for((var) = LIST_FIRST(head);					\
                (var)!= LIST_END(head);					\
                (var) = LIST_NEXT(var, field))

        /*
         * List functions.
         */
        #define	LIST_INIT(head) do {						\
            LIST_FIRST(head) = LIST_END(head);				\
        } while (0)

        #define LIST_INSERT_AFTER(listelm, elm, field) do {			\
            if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)	\
                (listelm)->field.le_next->field.le_prev =		\
                    &(elm)->field.le_next;				\
            (listelm)->field.le_next = (elm);				\
            (elm)->field.le_prev = &(listelm)->field.le_next;		\
        } while (0)

        #define	LIST_INSERT_BEFORE(listelm, elm, field) do {			\
            (elm)->field.le_prev = (listelm)->field.le_prev;		\
            (elm)->field.le_next = (listelm);				\
            *(listelm)->field.le_prev = (elm);				\
            (listelm)->field.le_prev = &(elm)->field.le_next;		\
        } while (0)

        #define LIST_INSERT_HEAD(head, elm, field) do {				\
            if (((elm)->field.le_next = (head)->lh_first) != NULL)		\
                (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
            (head)->lh_first = (elm);					\
            (elm)->field.le_prev = &(head)->lh_first;			\
        } while (0)

        #define LIST_REMOVE(elm, field) do {					\
            if ((elm)->field.le_next != NULL)				\
                (elm)->field.le_next->field.le_prev =			\
                    (elm)->field.le_prev;				\
            *(elm)->field.le_prev = (elm)->field.le_next;			\
            _Q_INVALIDATE((elm)->field.le_prev);				\
            _Q_INVALIDATE((elm)->field.le_next);				\
        } while (0)

        #define LIST_REPLACE(elm, elm2, field) do {				\
            if (((elm2)->field.le_next = (elm)->field.le_next) != NULL)	\
                (elm2)->field.le_next->field.le_prev =			\
                    &(elm2)->field.le_next;				\
            (elm2)->field.le_prev = (elm)->field.le_prev;			\
            *(elm2)->field.le_prev = (elm2);				\
            _Q_INVALIDATE((elm)->field.le_prev);				\
            _Q_INVALIDATE((elm)->field.le_next);				\
        } while (0)

        /*
         * Simple queue definitions.
         */
        #define SIMPLEQ_HEAD(name, type)					\
        struct name {								\
            struct type *sqh_first;	/* first element */			\
            struct type **sqh_last;	/* addr of last next element */		\
        }

        #define SIMPLEQ_HEAD_INITIALIZER(head)					\
            { NULL, &(head).sqh_first }

        #define SIMPLEQ_ENTRY(type)						\
        struct {								\
            struct type *sqe_next;	/* next element */			\
        }

        /*
         * Simple queue access methods.
         */
        #define	SIMPLEQ_FIRST(head)	    ((head)->sqh_first)
        #define	SIMPLEQ_END(head)	    NULL
        #define	SIMPLEQ_EMPTY(head)	    (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
        #define	SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)

        #define SIMPLEQ_FOREACH(var, head, field)				\
            for((var) = SIMPLEQ_FIRST(head);				\
                (var) != SIMPLEQ_END(head);					\
                (var) = SIMPLEQ_NEXT(var, field))

        /*
         * Simple queue functions.
         */
        #define	SIMPLEQ_INIT(head) do {						\
            (head)->sqh_first = NULL;					\
            (head)->sqh_last = &(head)->sqh_first;				\
        } while (0)

        #define SIMPLEQ_INSERT_HEAD(head, elm, field) do {			\
            if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)	\
                (head)->sqh_last = &(elm)->field.sqe_next;		\
            (head)->sqh_first = (elm);					\
        } while (0)

        #define SIMPLEQ_INSERT_TAIL(head, elm, field) do {			\
            (elm)->field.sqe_next = NULL;					\
            *(head)->sqh_last = (elm);					\
            (head)->sqh_last = &(elm)->field.sqe_next;			\
        } while (0)

        #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
            if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
                (head)->sqh_last = &(elm)->field.sqe_next;		\
            (listelm)->field.sqe_next = (elm);				\
        } while (0)

        #define SIMPLEQ_REMOVE_HEAD(head, field) do {			\
            if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
                (head)->sqh_last = &(head)->sqh_first;			\
        } while (0)

        /*
         * Tail queue definitions.
         */
        #define TAILQ_HEAD(name, type)						\
        struct name {								\
            struct type *tqh_first;	/* first element */			\
            struct type **tqh_last;	/* addr of last next element */		\
        }

        #define TAILQ_HEAD_INITIALIZER(head)					\
            { NULL, &(head).tqh_first }

        #define TAILQ_ENTRY(type)						\
        struct {								\
            struct type *tqe_next;	/* next element */			\
            struct type **tqe_prev;	/* address of previous next element */	\
        }

        /* 
         * tail queue access methods 
         */
        #define	TAILQ_FIRST(head)		((head)->tqh_first)
        #define	TAILQ_END(head)			NULL
        #define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
        #define TAILQ_LAST(head, headname)					\
            (*(((struct headname *)((head)->tqh_last))->tqh_last))
        /* XXX */
        #define TAILQ_PREV(elm, headname, field)				\
            (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
        #define	TAILQ_EMPTY(head)						\
            (TAILQ_FIRST(head) == TAILQ_END(head))

        #define TAILQ_FOREACH(var, head, field)					\
            for((var) = TAILQ_FIRST(head);					\
                (var) != TAILQ_END(head);					\
                (var) = TAILQ_NEXT(var, field))

        #define TAILQ_FOREACH_REVERSE(var, head, headname, field)		\
            for((var) = TAILQ_LAST(head, headname);				\
                (var) != TAILQ_END(head);					\
                (var) = TAILQ_PREV(var, headname, field))

        /*
         * Tail queue functions.
         */
        #define	TAILQ_INIT(head) do {						\
            (head)->tqh_first = NULL;					\
            (head)->tqh_last = &(head)->tqh_first;				\
        } while (0)

        #define TAILQ_INSERT_HEAD(head, elm, field) do {			\
            if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)	\
                (head)->tqh_first->field.tqe_prev =			\
                    &(elm)->field.tqe_next;				\
            else								\
                (head)->tqh_last = &(elm)->field.tqe_next;		\
            (head)->tqh_first = (elm);					\
            (elm)->field.tqe_prev = &(head)->tqh_first;			\
        } while (0)

        #define TAILQ_INSERT_TAIL(head, elm, field) do {			\
            (elm)->field.tqe_next = NULL;					\
            (elm)->field.tqe_prev = (head)->tqh_last;			\
            *(head)->tqh_last = (elm);					\
            (head)->tqh_last = &(elm)->field.tqe_next;			\
        } while (0)

        #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {		\
            if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
                (elm)->field.tqe_next->field.tqe_prev =			\
                    &(elm)->field.tqe_next;				\
            else								\
                (head)->tqh_last = &(elm)->field.tqe_next;		\
            (listelm)->field.tqe_next = (elm);				\
            (elm)->field.tqe_prev = &(listelm)->field.tqe_next;		\
        } while (0)

        #define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
            (elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
            (elm)->field.tqe_next = (listelm);				\
            *(listelm)->field.tqe_prev = (elm);				\
            (listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
        } while (0)

        #define TAILQ_REMOVE(head, elm, field) do {				\
            if (((elm)->field.tqe_next) != NULL)				\
                (elm)->field.tqe_next->field.tqe_prev =			\
                    (elm)->field.tqe_prev;				\
            else								\
                (head)->tqh_last = (elm)->field.tqe_prev;		\
            *(elm)->field.tqe_prev = (elm)->field.tqe_next;			\
            _Q_INVALIDATE((elm)->field.tqe_prev);				\
            _Q_INVALIDATE((elm)->field.tqe_next);				\
        } while (0)

        #define TAILQ_REPLACE(head, elm, elm2, field) do {			\
            if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL)	\
                (elm2)->field.tqe_next->field.tqe_prev =		\
                    &(elm2)->field.tqe_next;				\
            else								\
                (head)->tqh_last = &(elm2)->field.tqe_next;		\
            (elm2)->field.tqe_prev = (elm)->field.tqe_prev;			\
            *(elm2)->field.tqe_prev = (elm2);				\
            _Q_INVALIDATE((elm)->field.tqe_prev);				\
            _Q_INVALIDATE((elm)->field.tqe_next);				\
        } while (0)

        /*
         * Circular queue definitions.
         */
        #define CIRCLEQ_HEAD(name, type)					\
        struct name {								\
            struct type *cqh_first;		/* first element */		\
            struct type *cqh_last;		/* last element */		\
        }

        #define CIRCLEQ_HEAD_INITIALIZER(head)					\
            { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }

        #define CIRCLEQ_ENTRY(type)						\
        struct {								\
            struct type *cqe_next;		/* next element */		\
            struct type *cqe_prev;		/* previous element */		\
        }

        /*
         * Circular queue access methods 
         */
        #define	CIRCLEQ_FIRST(head)		((head)->cqh_first)
        #define	CIRCLEQ_LAST(head)		((head)->cqh_last)
        #define	CIRCLEQ_END(head)		((void *)(head))
        #define	CIRCLEQ_NEXT(elm, field)	((elm)->field.cqe_next)
        #define	CIRCLEQ_PREV(elm, field)	((elm)->field.cqe_prev)
        #define	CIRCLEQ_EMPTY(head)						\
            (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))

        #define CIRCLEQ_FOREACH(var, head, field)				\
            for((var) = CIRCLEQ_FIRST(head);				\
                (var) != CIRCLEQ_END(head);					\
                (var) = CIRCLEQ_NEXT(var, field))

        #define CIRCLEQ_FOREACH_REVERSE(var, head, field)			\
            for((var) = CIRCLEQ_LAST(head);					\
                (var) != CIRCLEQ_END(head);					\
                (var) = CIRCLEQ_PREV(var, field))

        /*
         * Circular queue functions.
         */
        #define	CIRCLEQ_INIT(head) do {						\
            (head)->cqh_first = CIRCLEQ_END(head);				\
            (head)->cqh_last = CIRCLEQ_END(head);				\
        } while (0)

        #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {		\
            (elm)->field.cqe_next = (listelm)->field.cqe_next;		\
            (elm)->field.cqe_prev = (listelm);				\
            if ((listelm)->field.cqe_next == CIRCLEQ_END(head))		\
                (head)->cqh_last = (elm);				\
            else								\
                (listelm)->field.cqe_next->field.cqe_prev = (elm);	\
            (listelm)->field.cqe_next = (elm);				\
        } while (0)

        #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {		\
            (elm)->field.cqe_next = (listelm);				\
            (elm)->field.cqe_prev = (listelm)->field.cqe_prev;		\
            if ((listelm)->field.cqe_prev == CIRCLEQ_END(head))		\
                (head)->cqh_first = (elm);				\
            else								\
                (listelm)->field.cqe_prev->field.cqe_next = (elm);	\
            (listelm)->field.cqe_prev = (elm);				\
        } while (0)

        #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {			\
            (elm)->field.cqe_next = (head)->cqh_first;			\
            (elm)->field.cqe_prev = CIRCLEQ_END(head);			\
            if ((head)->cqh_last == CIRCLEQ_END(head))			\
                (head)->cqh_last = (elm);				\
            else								\
                (head)->cqh_first->field.cqe_prev = (elm);		\
            (head)->cqh_first = (elm);					\
        } while (0)

        #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {			\
            (elm)->field.cqe_next = CIRCLEQ_END(head);			\
            (elm)->field.cqe_prev = (head)->cqh_last;			\
            if ((head)->cqh_first == CIRCLEQ_END(head))			\
                (head)->cqh_first = (elm);				\
            else								\
                (head)->cqh_last->field.cqe_next = (elm);		\
            (head)->cqh_last = (elm);					\
        } while (0)

        #define	CIRCLEQ_REMOVE(head, elm, field) do {				\
            if ((elm)->field.cqe_next == CIRCLEQ_END(head))			\
                (head)->cqh_last = (elm)->field.cqe_prev;		\
            else								\
                (elm)->field.cqe_next->field.cqe_prev =			\
                    (elm)->field.cqe_prev;				\
            if ((elm)->field.cqe_prev == CIRCLEQ_END(head))			\
                (head)->cqh_first = (elm)->field.cqe_next;		\
            else								\
                (elm)->field.cqe_prev->field.cqe_next =			\
                    (elm)->field.cqe_next;				\
            _Q_INVALIDATE((elm)->field.cqe_prev);				\
            _Q_INVALIDATE((elm)->field.cqe_next);				\
        } while (0)

        #define CIRCLEQ_REPLACE(head, elm, elm2, field) do {			\
            if (((elm2)->field.cqe_next = (elm)->field.cqe_next) ==		\
                CIRCLEQ_END(head))						\
                (head).cqh_last = (elm2);				\
            else								\
                (elm2)->field.cqe_next->field.cqe_prev = (elm2);	\
            if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) ==		\
                CIRCLEQ_END(head))						\
                (head).cqh_first = (elm2);				\
            else								\
                (elm2)->field.cqe_prev->field.cqe_next = (elm2);	\
            _Q_INVALIDATE((elm)->field.cqe_prev);				\
            _Q_INVALIDATE((elm)->field.cqe_next);				\
        } while (0)

    }
}
#endif	/* !_SYS_QUEUE_H_ */
